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1.3 Change Control & Configuration Management (ECR/ECO/Deviation control)

Quality engineering is not just about inspecting what was made; it is about verifying what should be made. Without robust Change Control, the "Golden Sample" becomes a myth, and production quality slowly degrades due to entropy. A Quality Engineer’s primary function here is not administrative; it is to act as the gatekeeper of the Validation Status. Every change invalidates a portion of the original qualification. The goal is to precisely identify that gap and close it before mass production resumes.

Configuration Management: The Basis of Inspection

You cannot inspect a moving target. Configuration Management (CM) establishes the Approved Product Baseline. This baseline is the only legal reference for Incoming Quality Control (IQC) and Final Quality Control (FQC).

Baseline Integrity:

  • Drawings & specs: Must match the Revision currently active in the PLM/ERP system.
  • Approved Vendor List (AVL): A resistor from a new vendor is a new part, even if the resistance is the same. Different sub-tier materials imply different reliability curves.

Revision Logic:

  • If a change impacts the Inspection Standard (dimensions, cosmetic criteria) -> Then the Revision must increment, and the Quality Plan must be updated.
  • If a sub-component changes (e.g., glue formula) -> Then re-validate reliability compliance, even if the top-level drawing appears unchanged.

ECR & ECO: The Re-Validation Trigger

The Engineering Change Order (ECO) is the mechanism that triggers a re-evaluation of the DFMEA (Design Failure Mode and Effect Analysis) and PFMEA (Process Failure Mode and Effect Analysis).

The Quality Assessment Filter:

When reviewing an ECR, ignore the commercial benefits. Focus solely on the Validation Delta.

  • If Material Change (e.g., Plastic Resin A to B) -> Then Require flammability, chemical resistance, and dimensional stability testing.
  • If Process Change (e.g., Manual screw to Auto-feed) -> Then Require torque consistency capability study (Cpk) and visual inspection for scratch risks.
  • If Tolerance Change (e.g., ±0.1mm to ±0.2mm) -> Then Verify stack-up analysis to ensure assembly fit is not compromised.

Pro-Tip: When a critical component changes, do not just approve the ECO. Require a "First Article Inspection" (FAI) and a localized reliability test (e.g., 5-piece drop test) specifically for the new configuration.

Disposition of Material:

The ECO must explicitly dictate the fate of existing inventory to prevent "mixed stock" quality spills.

  • Scrap: Physical destruction required. Certificate of Destruction (CoD) mandated for high-value items.
  • Rework: Rework instructions must be validated by Quality Engineering before execution. Post-rework yield must be tracked.
  • Use-As-Is: Only permissible if the non-conformance has zero impact on Safety, Reliability, or Customer Experience.

Deviation Control: Managing Risk Exposure

A Deviation (or Concession) is a formal agreement to accept a Non-Conformance. It is not a "fix"; it is a risk acceptance record.

Deviation Rules of Engagement:

  • If the deviation affects a Safety Critical Characteristic (SCC) -> Then Reject immediately. No waivers on safety.
  • If the deviation is cosmetic -> Then Establish "Boundary Samples" (Limit Samples) signed by the Quality Manager to guide inspectors on the line.
  • If the deviation is approved -> Then Implement 100% Screening or tighter AQL levels (e.g., Level III) for the duration of the deviation.

Traceability is Non-Negotiable:

Units produced under a deviation must be traceable. Record the specific Batch ID or Serial Number range. If field failures occur later, you must be able to isolate exactly which units were built under the concession.

Final Checklist

Control Point

Quality Action

Validation Delta

ECO must define specific tests required to re-qualify the change (e.g., Thermal, Drop, EMC).

Document Alignment

Ensure IQC/FQC Inspection Instructions are updated simultaneously with the ECO release.

Stock Purge

Verify physical segregation of Old vs. New Revision parts. 0% Mixed Stock.

Deviation Containment

Approved deviations must include increased Sampling Frequency or 100% Screening.

AVL Control

Alternate Sources must undergo the same qualification rigor as the primary source.

Rework Validation

Never release Rework instructions without a verified Method Statement and Retest Plan.

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